350-401 Question 443
Single answerA company is designing its OSPF network topology to optimize performance and minimize routing overhead. The OSPF Area 0 (backbone) connects to multiple normal areas as well as one area that has limited resources and does not require external routes. The company decides to configure this resource-constrained area as a special area type to reduce the size of its routing table. Which OSPF area type should the company use?
- A
Stub Area
- B
Totally Stubby Area
- C
Not-So-Stubby Area (NSSA)
- D
Transit Area
Show answer and explanation
Correct answer: B
Explanation
A Totally Stubby Area is the best choice for a resource-constrained area that does not require external routes. By blocking both inter-area (Type-3 LSAs) and external routes (Type-5 LSAs), it minimizes the routing table size and reduces the processing overhead on routers within the area. This makes it ideal for areas with limited resources.
- A. Incorrect.
Stub areas block external routes (Type-5 LSAs) but still allow inter-area routes (Type-3 LSAs). While this reduces routing table size, it does not minimize it as much as a Totally Stubby Area.
- B. Correct.
Totally Stubby Areas block both external (Type-5 LSAs) and inter-area routes (Type-3 LSAs), significantly reducing the routing table size. This is the most suitable choice for a resource-constrained area that does not need external routes.
- C. Incorrect.
Not-So-Stubby Areas (NSSA) are used to import external routes into an area while still limiting external routes from other areas. This is not applicable in this scenario since the area does not need external routes.
- D. Incorrect.
A Transit Area is used to interconnect other OSPF areas, typically in a hub-and-spoke topology. It is not used to reduce routing table size.